Plywood size framing house

I need to replace some plywood and insulation under the vinyl siding which frames my house when a contractor comes to replace an existing window with a smaller one. How do I know the size of the plywood and insulation? I have an interior wall down where the window is located, and I drilled a small hole so I could shove a make-shift depth guage in there. It seems to be 3/4" plywood. Does that sound right? And I peaked at the insulation the siding guys installed over it... it looks kind of blue and might be about 1/2" thick. Does that sound right too? I just need to know what to buy at HD before this guy comes... suggestions? Thanks!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Near the window, you could drill, from the exterior, through the siding and sheathing with a small hole saw. The insulation and plywood slugs will remain in the saw blade when extracted. Bill

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.